Hello,
I've got some valuable feedback from Roman (cc:) that the magic numbers of the legacy and the newer LZ4 formats do not match, hence with the current patch U-Boot would try to handle the legacy "lz4 -l"-compressed kernel as a raw/uncompressed image.
Since U-Boot itself supports only the newer lz4 format [1], apparently the best we can do is detect the legacy lz4 format and report it is unsupported. If no comments, this will be taken care of in v3.
[1] Quote from https://github.com/trini/u-boot/commit/027b728d4aafb5cf97abc804944a77b837b0f... NOTE: This implements the release version of the LZ4 frame format as generated by default by the 'lz4' command line tool. This is not the same as the outdated, less efficient legacy frame format currently (2015) implemented in the Linux kernel (generated by 'lz4 -l'). The two formats are incompatible.
Best regards, Eugeniu.